Fuel-pusher mechanism for stokers



o. CRAIGl FUEL PUSHER MECHANISM FORI-STOKERS DMn 11, 192s. l 1,695,229

Filed April 17, 1924 2 Sheets-Sheet l HTTOR N5 Y o. CRAIG FUEL PUSHER MECHANISM FOR STOKERS Filed April 17, 1924 2 Sheets-Sheet 2 I I I I I I l I I I 1 I l B @1MM Patented Dec. 11, 1928.

UNITED STATES PATENT OFFICE.

OLLISON CRAIG, 0F WORCESTER, MASSACHUSETTS, ASSIGNOR TO RILEY STOKER COR- PORATION, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHU- SETTS.

FUEL-PUSHER MECHANISM FOR STOKERS.

` Application filed April 17, 1924:.V Serial No. 707,258.

My invention relates to furnace stokers and more particularly to an underfeed retort stoker having a main longitudinal retort and branch retorts of the general type shown m the patent to Armstrong et al. No. 1,333,696 of March 16, 1920.

A retortstoker of this type is a strictly underfeed stoker in which the coal is fed by a plunger thru a main longitudinal retort and then laterally into parallel retorts and over dump plates at the ends thereof. 1n order to assist the distribution and movement of the coal in the side retorts, the longitudinal channel and the side retorts have been provided with reciprocating pusher blocks Which serve to feed the fuel forward from the point of entrance to the far end of each of the lateral channels.

As heretofore constructed, the pusher blocks in the branch retorts have been connected with a driving mechanism to move simultaneously in the .same direction, and this has resulted in imperfect operation of the stoker. 1n an underfeed furnace of this f type, the coal tends to coke and frit together in the retort below the burning Zone, whereas it is important that the fuel remain loose and in small pieces so that the air may percolate freely for the purposes of combustion. 1 have found that if the pusher blocks in the branch retorts are moved simul taneously in the same direction, these coked and fritted portions are not broken up to a satisfactory extent. When the pusher blocks move together in one direction, the coal is moved in that direct-ion and when the pusher blocks return, the coal is merely moved as a body in the other direction. Consequently the fuel beds in adjacent retorts are not readily broken apart and kept in proper condition for perfect combustion.

It is accordingly an object of my invention to overcome these difficulties and to provide a mechanism for stoker furnaces of this type which Will provide a slicing action between adjacent fuel beds and break up the fuel and reduce the tendency for it to coke into large masses, and Which Will insure greater efliciency than heretofore obtainable in such furnaces.

With this and other objects in view, as Will be apparent to one skilled in the art, my invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing in which like numerals indicate like parts:

Fig. 1 is an end elevation of the essential parts of the branch pusher block mechanism, the related portions of the stoker being shown diagrammatically in dotted lines;

Fig. 2 is a detail corresponding to Fig. 1 in which the pusher' blocks are shown in a second position;

Fig. 3 is a fragmentary elevation and vertical section on the line 3-3 of Fig. 1, With parts removed, to show the arrangement of operating shafts, bearings, and crank arms;

Fig. 4 is a top plan view of the stoker with various parts removed for the .sake of clarity of illustration;

Fig. 5 is a fragmentary vertical section showing the relation of the pusher in the main i retort channel to those in the branch retorts;

F 6 is a View corresponding to Fig. 1 showing the application of this invention to a retort stoker having branches on one side only; and

Fig. 7 is a diagrammatic vieW of an arrangement in which one set of the branch retort pushers are movable independently of the other set.

Referring to the drawings which illustrate one embodiment of my invention, 1 have there shown in Figs. 1 to 5 inclusive a stoker of a Well-known type, such as shown in the patent to Armstrong No. 1,333,696, in which the fuel is fed from an outside coal hopper 10 by means of a suitable. ram 11 thru the throat 12 into the longitudinal retortchannel 13 and -thence laterally into the side retorts 14. As is understood,these branch retorts are separated by sloping Walls on the upper portions of which are mounted tuyere blocks 15 through Which air is admitted from the Wind boX beneath the retorts to the fuel bed in the combustion zone. The coal moves upwardly through these lateral channels up the sloping bottoms 1G thereof and onto the side dump plates 17 from which the remaining ash falls into the ash pit.

Mounted for reciprocation lengthwise of the main channel 13 of the retort is a plate 2() having pusher blocks 21 thereon; These blocks as illustrated have gradually sloping faces 22 on their forward sides and steep or vertical faces 23 on the rear, so that the latter faces will push the coal toward the rear of the furnace and the former will raise the coal bed as the sliding plate 2O returns. rIhis plate is suitably connected with the ram ll, as by means of an arm 24 depending from the ram through a slot in a plate 25 connected to the slide plate 20, whereby the plate 20 and its attached blocks, which form the bottom of the main fuel channel, will reciprocate with the ram.

(lne simple form of pusher mechanism for moving the coal in the branch, retorts comprises pusher blocks 29 and 3() reciprocably mounted beneath the main pusher plate 20. rlhese blocks 29 and 30 are of such length as to project beyond the plate 2O into the branch retorts and the projecting portions are provided with sloping walls 3l and vertical shoulders 32 and 33 which as constructed serve both to move the coal forward and to raise it vertically.

ln the modification shown in Fig. 6, the pusher block may be made one-sided as illustrated since it is necessary to push the coal only in one direction. The other features of this stoker are similar to those shown in the other figures except that one side of the main retort is closed by a wall 35.

@ne suitable form of mechanism for reciprocating the branch retort pusher blocks may be made as illustrated. This comprises a pair of rock shafts 40 and 4l which are con nected by a linkage mechanism to the piston rod of a steam cylinder a2, diagrammatically illustrated in Figs. l and 1l. These rock shafts are suitably mounted in bearings 43 and all properly supported on I-beams Lio built into the furnace construction and located beneath the stoker. The upper rock shaft 40 has a crank arm L7 keyed thereto and this is in turn connected by a short link i8 to the slide 49 which is operated by the piston rod of the steam engine. The lower shaft similarly has a crank arm 50 keyed on one end and connected by a link 5l to another arm 52 fixed on the end of the upper rock shaft 40 so that as the piston rod reciprocates the two rock shafts move in the saine direction in unison. The shafts Ll0 and el move in the same direction, but since the arm 59 project-s below the shaft et() and the arm 57 projects above the shaft l1' it will be seen that when the arm 59 moves to the right the arm 57 will move to the left, thus causing `the pusher blocks 29 and 30 to move in opposite directions at the same time.

The pusher blocks 30 have downwardly projecting lugs 55V to each of which is pivotally connected a long link 56. rlhe other end of each link 56 is pivotally connected to a short crank arm 57 keyed to the rock shaft 41. Each of the blocks 29, which are arranged alternately with blocks 30 is similarly connected by a link 58 with a crank arm 59 project ing from the shaft 40.

ln the stoker shown in lfig. 6, the engine cylinder is shown as mounted to reciprocate its piston vertically and the linkages are changed correspondingly. ln this construction, the arm 6() on the lower shaft el is connected by a link 6l to the arm 62 attached to the shaft 40, and both are connected by link 63 to the piston rod slide 64s. The arm 65 fi ed on the shaft ll is connected by a link 66 with the pusher block 9G. Similarly the block 91 is connected by a link 67 to the arm 68 fastened to the shaft 40.

rlhese linkages are so arranged that the sets of blocks and 91 will reciprocate in opposite directions at the same time and this is accomplished by properly positioning the arms 65 and 68 on their respective rock shafts. By changing the positions of these crank arms, the relative motions of the two blocks 90 and 91 may be correspondingly changed.

`W ith the arrangement above described, the two sets of branch retort pusher blocks are in- Vtended to be operated by the same prime mover to reciprocate in opposite directions at the same time. ln certain cases l. prefer that the two sets of pusher blocks be moved independently of each other, and to this end l provide a mechanism such as shown diagrain n'xaticaily in Fig. 7. As there illustrated, the set of blocks 92 may be mechanically operated, the same as the corresponding parts 29 shown in Fig. l, by means of the links ZO pivotally connecting the blocks with arms 7l de.- pending from the rock shaft l0 which is rocked by means of the lever 73 connected by a link ML to the piston rod slide 75 actuated by the engine cylinder 76. The other set of blocks 93 corresponding with the blocks 30 shown in Fig. l is arranged to be actuated by a separate and independent engine which may if desired be connected through a suitable valve mechanism with the other engine so that the two may be operated together or independently. illustrated, the links 78 which are pivotally connected to the blocks V3 are adapted to be actuated by arms 7 9 keyed to the rock shaft al, and this shaft is arranged to be rocked b-y means of a lever 8l rigidly fastened thereto which is connected by a link 82 with the piston of a steam c-ylinder 83.

lilith this construction it is feasible to operate the two sets of pusher blocks independently of each other in whatever manner is indicated by the condition of the fuel bed in the furnace. For example, the sets of pusherblocks 93 may be moved in alternate retorts and then held stationary while the blocks 92 are moved in the same or opposite direction, or adjacent pushers may be reciprocated alternately in opposite directions at the same time as above described. One set may be moved faster than another to meet temporary conditions in the furnace or they may be otherwise operated as will be apparent to one familiar with stolzer furnace practice.

It will therefore be seen that I have provided a simple mechanical construction whereby fuel is fed longitudinally of the main retort 13 and is assisted in such movement by the slide 2O carrying the fuel pushing and lifting blocks 21. From this main retort fuel is moved by pushers 29 and 30 towards the ends of the branch retorts, and it is repeatedly lifted and stirred about. In my preferred construction as shown in Fig. 1, a single pusher, 29 or 30, is used to move the fuel in opposite branch retorts, so that when the fuel in, say, the first branch retort on the left hand side is moving outwardly, the fuel in the adjacent retort is substantially stationary. At the same time the fuel in the first right hand retort is stationary and that in the second retort adjacent thereto is moving outwardly. rIhis movement of the pushers results in a slicing action between the two bodies of fuel thus tending to brealr up any large clinlrers or fritted masses that may have formed. The pushers 29 and 30 are movable independently of the pusher 21, and their relative rates of operation may be, suitably adjusted as determined by conditions within the furnace. The operation of thedevices shown in Figs. 6 and 7 will be readily apparent in view of the above explanation.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A stoler having stationary walls formingl a main retort and branch retorts connected therewith, means to feed fueln into the main retort, mechanism including fuel pushers located in the branch retorts arranged to move the fuel away from the main retort, and means to operate the pushers in adjacent branch retorts in opposite directions at the same time.

2. A Stoker comprising walls defining a main retort and branch retorts communicating therewith, a pusher member movable lengthwise of the main retort, pushers beneath said member and movable laterally into the branch retorts and means to move the pushers in adjacent branch retorts simultaneously in opposite directions.

3. A stolrer furnace havinga main retort and branch retorts connected therewith, a ram to feed fuel into the main retort, pushers in adjacent branch retorts arranged to move the coal outwardly, two shafts and connections from alternate pushers to one shaft and from the other pushers to the other shaft, and means to move said shafts and operate adjacent pushers in opposite directions at the same time.

4. A stolzer having a main retort and branch retorts connected therewith, means to push fuel longitudinally of the main retort, pusher blocks in the branch retorts, two power operated movable members, connections between alternate pusher blocks and one of said members, connections between the other pusher blocks and the other power operated member, and connections between said power operated members so arranged that the fuel beds in adjacent branch retorts are moved simultaneously in opposite directions by said pusher blocks.

Signed at Viorcester, Massachusetts, this 14th day of April, 1924.

OLLISON CRAIG. 

